<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script type="text/javascript">
    console.log("我是控制台输出");
    console.log("我是控制台输出");
    console.log("我是控制台输出");
    document.write("我是页面输出<br/>");
    alert("我是弹窗输出...");

    // 定义变量
    let a1;
    a1 = 10;
    a1 = 3.14;
    a1 = "helloWorld";
    a1 = false;
    a1 = new Object();
    // 进行赋值
    a1.age = 10;
    a1.name = "张三";
    a1.height = 171.3;
    console.log(a1);
    // 进行赋值
    a1 = {name: "张三", age: 18};
    // 进行输出
    alert(a1.age);
    alert(a1.name);
</script>
</body>
</html>